Bilateral presentation of anything is uncommon in comparison to unilateral, bilateral leg issues like muscle weakness, spasms, clonus, foot drop etc can still happen more common in MS over time from further lesion damage though, bilateral is still generally not expected to be equally the same on both sides (symmetrical).
Keep in mind that 'MS fatigue' can make it feel like both legs or your entire body is weaker by the end of the day, it depends on how active you are, how much proactive resting your doing and where your energy is being focused to and being used up by....
Your an MSer so your bucket of energy has a hole in it, and everything you do takes more away until eventually it's run out but your just so busy right, you don't have time to stop and put off what needs doing......if you aren't resting and managing your day's energy and topping up your energy bucket throughout the day, your energy just keeps running out earlier and earlier from one day to the next and the fatigue makes you get weaker and weaker.
eg. You live a busy active life: you get up in the morning and busily run around all day long doing your thing, sure like anyone you'd sometimes feel tired by the end of the day but not so tired that you couldn't keep going and tomorrow you do it all again..
You live an active life: 'MSer' you get up in the morning and already your not fully rested after 8 hours sleep because you pushed your self getting through all of yesterdays activity but your still busy, so you keep running around all day long doing your thing, having to push it even harder today and boy are you feeling wrecked and the day isn't over yet.......you get up in the morning with even less energy than yesterday etc
Your newly dx and it can take a year or two before you get your head around MS and it can be very hard to recognise your bodies signs that you need to slow down and take a brake. It's unlikely that what you are currently experiencing is progression or transference into SPMS and more likely the more common issue of MS fatigue because your still trying to do everything and paying the MS toll.
Before you let your self think your just not working out enough, or need more PT, think about what your doing and if your doing to much, see if you can rework your day a little better. Also look at any of the side effects of your medications, some actually help with one issue but make you fatigue more easily. I also know skinny though it's genetics not by choice, i've always burned calories too easily, with the tremors I now need to fuel up more for the energy i'm using up on an average day, more active days and i need even more fuel.....
I appreciate you both so much. I do fill my day with a lot. There's so much to do!! I need to manage it better. Especially around the holidays. Being dx older though., I'm 46.. I was thinking spms will arrive sooner. I Need to remember. One day at a time. Sigh. Thx again!!!
Transference to SPMS isn't associated to the 40-50 age group the way PPMS is, decades ago before DMD's became available there use to be a 15-20 year average time frame before RRMS transferred to SPMS. So before DMD's, it was more common to go into SPMS in your 40's to 50's but DMD's changed the history of MS, and that isn't the expected out come for MSers any more.
Theoretically today, regardless of what age ( 20's, 30's, 40's, 50's etc) someone has their 'first' MS attack, if they continue taking a DMD and it does slow down and keeps their disability scales low etc, today's MSer may never actually ever transfer from RRMS to SPMS.
Hope that makes sense :D